To remove the inner barrel assembly take the 3/32" pin punch and knock out the pin I am pointing to. Be sure to support the plastic outer barrel so you don't break it.

Once the pin is out, carefully take out the inner barrel. There will be a little cylinder shaped piece with a hole in the middle that comes out with it. Be sure not to lose it or the pin. Now take the inner barrel assembly and grab a 1/16" pin punch
and knock out both of these pins

Now that those two pins are removed, this piece can be taken out:

Now take the small phillips head screwdriver and take this screw out

Take off the piece the screw is holding in along with the screw itself. Now carefully twist the hop up hood (the part that the hop up tool twists) Be VERY careful when doing so, this is how you get the ball bearing out. Your bucking will not be blue. I don't know what happened to the picture I originally took to show this because it's not showing up on my uploaded pictures. I have this picture instead which is the same exact thing but with my blue falcon bucking that I took when assembling the hop up.

Take out the ball bearing and put it in a very safe place. Now that it's out you can safely slide the barrel like so:
Keep in mind the way the barrel is designed you can't slide it out of the chamber in that direction.
Now slide the hop up hood back:
Once the hood is back you can take off the bucking which I already did for the picture.
Then you can also take the hood off by sliding it in the same direction you slid the bucking off.
To remove the barrel, slide it so the side that is cut for a bucking is the last to leave the hop up chamber. Now everything is disassembled!

Now to reassemble.
For reassembly I am going to be replacing my bucking with a blue one made by falcon that seems more durable than the original and does not swell to silicon like the original either.
First, put the barrel back in the chamber housing if you took it out. Once it is in the hop up chamber, put the hop up hood on the same way it was taken off. Also reinstall the bucking but NOT THE BALL BEARING YET. I did install the bearing in the picture but just ignore that. You do not need to grease the bucking like you would with an aeg.
Slide the bucking back so the cutout for the ball bearing is under the hop up hood. Now the ball bearing can be installed onto the bucking. It should now look like this:
Next, very carefully twist the barrel so the bearing goes under the hood:
Twist the barrel about 180 degrees so the bearing is on the opposite side of the opening that is shown in the above picture. Next, install this piece, I forgot to mention the piece for disassembly but by now you probably already know about it :
Then slide the barrel/bucking assembly all the way into the chamber. Be sure to match the rectangular part of the piece shown above with the cutout for it in the hopup chamber.
Next put this piece back on:
Use the 1/16" pin punch to get the roll pins back in. Now its time to center the hop up mound (the part that actually puts the hop on the bb.) First, twist the hop up hood so it looks like this:
Doing that turns the hop up off. Now the bearing isn't putting any pressure on the bucking because if it is while you are going to be twisting the barrel, you will damage the bucking.
Okay, hold the hop up hood and get a good grip on it (part circled in white) and twist the barrel (circled in black) until the hop up mound is centered. Be sure not to twist the barrel and have all the time you spent centering the mound wasted. Once it is centered it is time to put the stabilizer (that's what I'm going to call it for the sake of this guide) back on. The "stabilizer" will make it so you can twist the hood with the hopup tool without the barrel moving with it. Installing it is the (simple) thing I struggled on when I was first finding out how to reassemble the hop up myself because there are NO other guides out there on how to assemble/disassemble the kwa m9/m93 hopup. What happened was I put on the stabilizer and screwed it in. But when I put it in the outer barrel, the inner barrel assembly did not move back and forth freely like it was supposed to which caused a lose of about 160FPS and the gun would jam or not even feed. I notice that it wasn't like that before I took it apart so I decided to look at what would cause the inner barrel assembly to rub against the outer barrel wall. What I found was the stabilizer was not flush with the hop up chamber and was the thing rubbing against the outer barrel. I took it off and I tried for 10 minutes to realign the barrel to get it to be flush with the chamber. After I took a break, I noticed something when I came back.
(*cough...I'm an idiot...cough.*) It is supposed to hook over the took of the hop up chamber. I looked at the chamber and saw this:
That's what it hooks over. Once I installed it like that I got it sitting flush like it is is supposed to be! After that, everything for the inner barrel assembly was together and working properly. What I tried to do before I knew about that was put the stabilizer on with the screw hole being the first to touch the chamber instead of the top of the stabilizer hooking over the chamber which caused it to stick out. Now it is time for final assembly into the outer barrel. Take the little cylinder thing with a hole in it that I mentioned to be careful not to lose, and install it into the cutout in the hop up chamber like so:
Once it is in try to keep it like it is in that picture, don't let it turn so that you can't see through the hole. Carefully insert the inner barrel assembly into the outer barrel. Line the cylinder up with the hole that the pin goes through. I use a flashlight to shine and see if it really is lined up. I find it easiest to put the 3/16" pin punch through the hole, through the cylinder, and out the other side (see picture) when the cylinder and the hole for the pin is lined up.
Then take the pin and put it through the hole with the pin punch still in so the little cylinder is kept aligned. Take a hammer and carefully knock the pin in which will push the pin punch out the other side but will keep everything aligned. BE SURE TO STABILIZE THE OUTER BARREL WITH YOUR FINGERS LIKE SO:
This way the outer barrel won't break. That's my trick to keep the cylinder aligned while knocking the pin through. After that's done you can carefully flex the outer barrel "flap" so you can see if the pin went through the little cylinder.
Now everything is assembled!

Make sure the inner barrel assembly can freely slide back and forth in the outer barrel. This is very important so the pistol will properly cycle and won't constantly jam (slide jam and/or bb jam.) It also gives the proper nozzle to bucking seal. Remember, when mine didn't move freely and caught against the outer barrel I lost about 160 FPS and got frequent jams. Once you ensure it moves freely, you can completely reassemble your m9/m93 and manually cycle the slide 4-5 times to assure nothing is catching. Next is the final functionality check test. Fire your pistol outside and adjust the hop up to ensure that it performs properly and the bb's are getting a proper stable flight pattern.
Congratulations! You have now successfully disassembled and reassembled your m9/m93's hop up!

Thanks, I spent like 3 hours putting this all together and then the pictures ended up being different then what I spent forever to arrange. Some pictures were in different order, some I had parts circled that I was talking about and the pictures showed up but the circles did not, and others pictures didn't want to show up at all. The website I used to circle things in the picture didn't like the format for forums so I'm now using a different website to do the same thing. Although, from the look of the few pictures of things circled I've uploaded I don't know why there are random lines elsewhere on the pictures. I might need to find a third program to do this. I would just buy a program but there's no reason to if I'm only going to use it for this. I've uploaded the raw pictures just for the sake of haveing a picture guide. I'm too tired to finish changing everything to how I wanted. I will make those final changes probably tomorrow.

Great work mate !!!, I wanted to make a guide just like this but just never seemed to get the time to do it!, I laughed when you spoke about not putting that little barrel bracket with the hook section back on correctly cause when I was puttting mine back together I did the same thing!!!.

I didnt actually have the gun all re-assembled but it took me a while before I figured out why the inner barrel kept turning in the hop up chamber!?, eventually I noticed that little hook section on the bracket.